i highly recommend changing all the other valvetrain when doing ctr cams
yes, I know you dont HAVE to...but theyre a lot more aggressive than standard b16's
the b16 and gsr heads flow almost the same...very very similar...but gsr does come out on top (something most dont know)
gsr is better in a way because of higher compression (square combustion chambers)
so if youre gonna boost...I would go b16 head because of the round chambers & lower compression
if going type r (real or ported b16), it would be cheaper (probably) to get the whole-shibang instead of building/porting a b16 head, plus it would be more reliable (oe honda=no chance for machine shop screw-ups) plus if you decided to go ctr pistons you could easier (dont fit b16 head w/o work...i believe)